FIGURE 3.

The GH–GHR–IGF1 axis may control mitochondrial function by regulating mitochondrial biogenesis and mitophagy. The effects of GH–GHR–IGF1 axis on mitochondrial function may be mostly mediated by IGF1, which stimulates several signaling pathways, including phosphoinositide-3-kinase (PI3K)/AKT and Ras/Raf/MAPK signaling, to further activate numerous transcription factors (TFs). This cascade leads to transcriptional activity of genes involved in both mitochondrial biogenesis and mitophagy. Accordingly, IGF1 is commonly considered to enhance mitochondrial function by promoting mitochondrial biogenesis and mitophagy under several conditions of metabolic or mitochondrial stress. However, whether there is an interaction between the mitochondrial biogenesis and mitophagy regulated by IGF1 is still unknown, and further research is needed.